Pulverized-fuel furnace



@vo 265 192@o H. R, CQLLHNS y PULVERIZED FUEL FURNACE Filed July 1, 1919 Newo 26 E929o H. R, COLLINS PULVERIZED FUEL FURNAC'E Filed 'July 1, 1919 j l NVENTO /ZQ,

BY 7 @@WQ//Lww/;

ATTORNEY vto Patented Nov., 26, llggtl een www

WRY la'lm CO'LLXNS, OF ALLENTOWN, PENNSYLVANIA, SSGNOR, BY MESNE SSKGNWENTS, 'EO-FULLER LEHGH COMPANY, A CORPORATION 0F DELAWARE PULVERXZED-F'UEL- EURNACE application fue@ July i; 191e. serial no. 307,850.

'llhisinvention relates to the use of pnlveripzed fuel in furnaces and is directed to the provision of a furnace of improved construction and a novel method of operation whereby superior results are obtained.

The usual practice in the utilization of fuel in .pulverized form is to introduce the fuel into the furnace in an air stream. In recent years the use of pulverized fuel in thefurnaces of stationary boilers has demonstrated the lgreat .importance of maintaining the .velocity of flow ofthe gases of combustion Vthrough the furnace very low, preferably under l0 feet per second. rlhe employment of this low velocity insures complete consumption of the fuel particles before they enter the space about the boiler tubes and greatly reduces erosion of the walls of the furnace, thereby effecting a corresponding increase 1n the life of the furnace.

ll have found that the proper introduction of pulverized coal in substantial quantity into the furnace of a stationary boiler does not require the admixture with the f uel of all of the air necessary for combustion of the fuel within the furnace. yllfrec flow of the fuel into the furnace can be effected with much less` air. rllhis being so, the balance of the air rcquired for combustion may be introduced otherwise than through the burner tube and may be utilized for effecting additional purposes. ll introduce -it' into vthe furnace in opposition to the general direction of travel` of the particles of pulverized 'fuel within' the furnace so that this additional supply of air exerts a sustaining effect on the particles of fuel and thereby lengthens the travel through the furnace.

'llhe method of operation which gives the best results is to introduce the pulverized fuel into the upper portion of the furnace in a wi de period "of thin stream and allow it to drop vertically by gravity, the volume and pressure of .the 'air -admitted with the fuel being just enough to -troducethroughit such additional air as is tically through the furnace and insures that they will be held in suspension such a length of time as will be ample for complete consumption of the combustible constituents of the fuel particles. The upwardly moving current of air also tends to carry the nonm combustible constituents of the liner fuel particles toward the upper regions of the furnace, from .which they are carried into the stack with the gaseous products of combustion.` The heavier non-combustible residues passA @5 through the relatively cool incoming air. as they approach the bottom of the furnace and are deposited'in granular or sand-like condition.

lt has been proposed heretofore to provide 70 a pulverized fuel furnace with a traveling gratey at the bottom thereof to carry 0H any deposit of the ash content of the lfuel. rl`he provision of such a traveling grate is very important for'several reasons. When the ash 75 i of pulverized fuel is deposited on a relatively cool surface at the bottom of the furnace, it takes a granular form, that is, there is considerable adhesion of the ash particles. But,

if the ash deposit is allowed to accumulate so to fil-'substantial depth, the bed of ash, or at least the portion thereof removed slightly from contact with the grate fuses into a solid mass under the influence of the high temperature existing in the furnace.y The slag thus formed can be removed only with a cony siderable expenditure` of time and labor.

N Furthermore, if an ash deposit is allowed to accumulate, it reduces the volume of the furnace with the result that the velocity of travel of the fuel and the gases of combustion through the furnace is correspondingly increased. Therefore, in the practice of my invention I employ a movable grate atthe bottom of the furnace for receiving the ash deposit anddischarging it in granular form into a pit from which it may be removed from time to time. The inlet forthe supplemental air stream which sustains the fuel particles and co-ols the non-combustible residues is 10 preferably placed below the grate so that the air lpasses upward through the grate to heep it cool and therebyassist` in cooling the ash'.

deposited upon it.

The particular nature of the invention vvill appear more clearly from a description of a preferred embodiment, and for this `purpose the furnace is shown in combination with a, Water tube boiler of standard form. llt Will be understood, however, that the invention not limited in its application to boilers, but may be used in pulverized fuel furnaces adapted for any other purpose. ln theaccompanying drawings, y

Fig. l is a longitudinal sectional View of the boiler taken along the line 14-1 of-Fig. 2;

Fig. 2 is a, view in elevation of the front end of the boiler With a section broken away;

Fig. 3 is an end View of some of the units of the mechanism for removing the residues of combustion; y

Fig. 4 is a plan view of these units showing the section 'line uponwhich Fig. 3 is taken; and.

Fig. 5 is a longitudinal section of part of one of the units along the line 5 5 of Fig. l.

Referring to the drawings in Which similar reference characters denote similar parts throughout the several views, the boiler has .a front wall 1, rear Wall 2 and side Walls 3, forming a combustion chamber 4; of relatively large volume and otherwise designed in accordance with the principles applicable to furnaces in which pulverized fuel is to be burned. The hot gases of combustion pass to the Water tubes 5 through a passage at the top of the combustion chamber and then to the stack. v

At the top of the combustion chamber is an arch 6, and extending through the arch is a nozzle 7, through Which'thepulverized fuel may be fed by anysuitable mechanism', which, since it forms no part of this invention, is not shown. The fuel nozzle may be of any suitable form, but preferably is provided With a narrou7 elongated mouth7 so that it projects the fuel into the combustion chamber in a thin cloud. Surrounding the nozzle 7 is a passageway 8, through which air may be sup-v plied to mix with the fuel, this air entering a chamber 9, having ports controlled by 'dampers 10, so that the supply of air may be regulated. Instead of admitting the fuel-laden air through the top of the furnace, it may be supplied through the front or side Walls of the furnace, as by means of a burner tube 11 of suitable construction.

The mechanism for removing the residues of combustion is mounted at the bottom of the combustion chamber and comprises 'aseries of hollow shafts 12, mounted in suitablejbearings 13 in a housing 14, forming the front Wall of the ash pit part of the boiler. A similar bearing 15 is provided in a housing 16 that forms .the rear Wall of the ash pit. lBoth of ser the housings 14 and 1S are provided with number of ports 17, having f 'ding dampers lll connected to a rod' 19, lea-ding an operating llever 20, whereby the eiitei'it of the opening of all of the apertures may be simultaneously controlled.

rllhe housings 14tand 15 are also provided with a number of doors 21, through which th-e residues of 4combustion may be removed after they have been dis- .of air to the combustion chamber maybe further regulated. l

, Uponthe shafts 12 are mounted a number of triangular castings 24, each having* a central aperture to receive the shaft and a number of smaller apertures to lpermit the airv to Vcirculate through the' castings. Each of the castings is .provided "on one side With a boss 26, preferably'of hexagonal form, and on the other side with a correspondingly shaped recess 27,so that when the several castings are assembled on a shaft they form a continuous grate extending across the combustion chamber. The front castings of alternate shafts are' provided With bosses 28, but the castings of the other shafts are Without any such bosses, so that when the castings are mounted upon the shafts, they will be staggered with relation to each other, as shown most clearly in Fig. 4. This arrangement permits the castings of each unit to move Without interfering with those of the adjacent units. The castings thus form, in

effect, fingers which Will break up anyl small `with a pinion 30.engaged by a Worm 31 having a.I pulley 32.\Wliich may be driven by a motor 33, or in any other convenient manner. 1

ln the operation of the boiler described above, pulverized fuel in `any desired amount..

is fed through the nozzle 7 under the influence of air pressure just sufficient to blot the fuel into the combustion chamber Without impartingto the products of combustion such a velocity as Will cause erosion of the furnace Walls.l If the nozzle has a Wide opening, the fuel Will enter the furnace in the formof a thin jet, and an induced current of air will enter on each side of the nozzle and 'maybe regulated by the dampers 10,. rllhe ILO ' "maceta combustion chamber, giving a longer passage of the flame and completing.combustion before strikingthe cold surfaces of the boiler.

rlhe draft through the stack of the furnace draws air into the ash pit through'the ports 17 and 23, and the amount of air taken. in through these ports can be adjusted to such a tine degree that an analysis of the stack Ygases can be made to give high percentages of carbon dioxide. the ash pit, it is atA the temperature of the atmosphere, and it will pass upwardly between and through the castings of the revolv-A ing grate and meet the descendingcolumn of burning fuel in the combustion chamber, holding the particles of fuel in suspension and supplying the oxygen required to com.- plete combustion. The upwardly moving current of cooler air will also tend to carry the finer particles of residue towards the stack, and thus prevent the deposit of large quantities of ash in the ash pit. The air which enters the furnace at substantially the temperature of the atmosphere will also cool the castings of the revolving grate andprevent them from becomingfused under the influence of the high temperatures prevailing in the combustion chamber.

As the air passes upwardly through the units of the revolving grate, it encounters the heavier particles of residue which are falling toward the grate, and cools them, so that the ash deposited on the grate will remain in granular or sand-like form and not tend to slag under the influence of the high temperatures in the combustion chamber. The units of the revolving grate are also further cooled by air which may circulate through the hollow shafts. During the operation of the furnace, the shafts are continuously rotated, so that thel residues deposited on the triangular castings will be discharged intothe ash pit, from which they may be remo'ved from time to time through the doors 21.

The removal of the ash in granular form from the heat zone of the combustion chamber is constant throughout the operation of the boiler, and .asithe ash is continually passing through a current of relatively cool air,

entering the ash pit, the possibility of slag formation is etectually prevented and the furnace may be kept continually in operation, it not being necessary -to shut it down for the purpose of removing the slag-like deposit, as is the case with furnaces of usual construction. On account of the continual removal of the residues of combustion, the initial volume of the combustion chamber will remain constant, andthis is essential tov is the air enters the ports in erosion and destruction of the walls of ,the chamber are more likely to occur.

While the inventionhas been showiiand described in connection with a standard form of boiler, 'it' will be understood that iti is equally applicable to any kind ofa furnace in which pulverized fuel is to be burned, and also that any other form of mechanism for removing the residues of combustion as fast as they areproduced, maybe employed in place of the one shown; yalthough the construction of the latter possesses many vadvantages which render it particularly adapted for use in the present relationslripi` lt will also be understood that the pulveri'zed f uel may be fed into the combustion chamber in any other manner and at the sides or front of the same, instead of at the top as shown in the present embodiment.

lI claim:

l. A steam boiler furnace combination of a combustion chamber, a burner for introducing fuel into the chamber for combustionv in suspension therein, and a metallic surface in the chamber maintained cooler than the combustion space 4of said chamber and positioned to receive particles falling from said combustion space, this Surface being out of the normal path of the fiaming stream fromthe burner and directly exposed to the combustion zone except for residues from said zone deposited thereon in normal operation.

2'. A steam boiler furnace comprising the combination of a combustion chamber, a burner for introducing fuel into the chamber for combustion in suspension therein, a metallic surface positioned to receive particles falling from the combustion 'spate of said chamber, said surface being out of the normal path of the flaming stream from the burner and directly exposed to the combustion zone except for residues from said zone deposited burner for introducing fuel into the chamber for combustion in suspension therein, a metallic surface positioned to receive particles falling from the combustion space of said chamber, said surface being out of the normal path of the fiaming stream from the burner and directly exposed to the combustion Zone except for residues from said Zone deposited thereon in normal operation, and means for causing a cooling medium to flow beneath said surface in Contact therewith to abstract heat therefrom. fr

4. A steam boiler furnace comprising the combination of` a combustion chamber, a burner for introducing fuel into the chamber for combustion in suspension therein, and a metallic surface cooler than the combustion space of said chamber positioned to receive particles falling from said combustion space, this surface including a plurality of spaced ,members extending across the chamber and being disposed out of the normal path of the ceive particles falling from said combustion space, this surface lying out of the normal path of the Haming stream from the burner and directly ex osed to the combustion zone except for'resi ues from said Zone deposited thereon in normal operation, the said surface including a plurality of -s aced metal mem-;

bers extending across t ie chamber and through the walls thereof and metal elements supported by said members.

6. A steam boiler furnace comprising the combination of a combustion chamber, a burner for introducing fuel into the chamber for combustion in suspension therein, a me tallic surface positioned to receive particles falling from the combustion space of said chamber and disposed out of the normal path of the flaming stream from the burner and directly exposed to the combustion zone except for residues from said zone deposited thereon in normal operation, said surface including a plurality of spaced metallic members extending across the chamber and metallic elements mounted on said members and extending between them, and means for causing ,a cooling medium to ilow in contact with said surface to abstract heat therefrom. x 7. A steam boiler furnace comprising the combination of a combustion chamber, a burner for introducing pulverized fuel into the chamber in a substantially vertically downward direction for combustion in suspension in the combustion space of said chamber, an outlet near the top of the chamber, the flaming fuel passing through the 'chamber in a reverting path flowing downwardly from the burner and upwardly to the outlet,

a metallic surface in the chamber positioned below the bend in the flaming stream and out of the normal path thereof and directly exposed to the combustion zone except for residues of combustion deposited thereon from said zone in normal operation, said surface serving to receive particles falling from the combustion space, and means for causing the flow of a cooling medium in contact with said surface to abstract heat therefrom. l

8. A method of burning fuel in'a combustion chamber which comprises continuously introducing, igniting, and maintaining the space of said chamber and positioned to re' combustion of fuel in pulverulent form in suspension in 'said combustion chamber, receivire refuse particles precipitating from the l i tion Zone on metallic surface in said combustion chamber, and abstracting heat from said surface by causing a cooling mcdium to"flow in contar"- with said surface throughout normal o ac on. 'to prevent substantial fusion of particles deposited on said surface from said combustion sone.

9. method of burning pulverulent fuel in a. combustion chL which comprises continuously introducing pulverulent fuel in asubstantially vertical downward direction into said chamber at a, point near the top thereof, igniting and maintaining combustion of said fuel in said chamber, withdrawing the products of combustion through an' outlet near the top of thechamber whereby the flaming stream flows from the point of vintroduction to the outlet along a substantially lll-shaped path, receiving particles falling from the combustion space of said chamber on a metallic surface belowr the point at which the stream turns upon itself, and abstracting heat from the said receivingr surface by causing a cooling medium to flow in Contact with said surface continuously, said heat abstraction being carried on4 to the extent sulhcient to prevent substantial fusion of particles deposited on said surface from the combustion zone,

10.' A. steam boiler furnace comprising the v combination of a combustion' chamber, a burner for introducing fuel into the chamber for combustion in suspension in a zone above the battom thereof, a plurality of V'spaced members in the chamber below the combustion zone and in the path of particles precipitating from said zone in normaloperation, said members being disposed out of the normal path of the flaming stream from the burner and directly exposed to the combustion Zone except for residues from said zone deposited thereon in normal operation, means for subjecting said members to the actionA of a cooling medium to maintain them at a temperature cooler than that of the 'combustion zone, and an ash-receiving surface disposed beneath said members and spaced therefrom for receiving particles passing said members. 11. A steam boiler furnacecomprising the,

vcombination of a combustion chamber, a

burner for introducing vfuel into the chamber in a substantially vertical downward direction for combustion in suspension in a Zone above the bottom of the chamber, an outlet from the chamber near the top thereof whereby the flaming stream from the burner flows back upon itself in its passage to the outlet and has a substantial U-shape, and a plurality of spaced members below the combustion zone in the path of particles precipitating from said zone in normal operation and extending across the chamber, said members being out ofthe normal path of the flaming stream from'the burner and directly exposed to the combustion zone except fof, residues from said zone deposited thereon in normal operation v means` for subjecting said members to the action of a'ycooling medium to maintain them at a temperature cooler A than that ofI the combustion space, and an ash-receiving surface disposed beneath said .lo members .and spaced therefrom to receive particles passing said spaced member-5,'

12; A steam boiler furnace dcomprising 'the combination of a combustion chamber., aburner for introducing fuel into the chamber 15 for' combustion in suspension-in a zone above the bottom thereof, a plurality of spaced me.-` tallic members in the chamber below -the combustion lzone in the path of particles-precipitating from Said zone in normal opraf y I tion, said members lying out of the normal path of the iiaming stream of the burner andrv directlyvexposed to the combustion Zone ex cept for residues deposited thereon in normal operation, means for causing a cooling medium to flow in contactwith said members to maintain them at atemperature cooler than that of thef'combustion zone, and Vanfash-receving surface disposed beneath saidmembers and at a distance therefrom to receive 30 particles passingsaid members.

v13. The method of' burning fuel ina combustion chamber` which comprises continu o'usly introducing, igniting, and maintain` ing the combustion of fuel inv pulverulent v form in suspension in a zone in the combustion chamber, receiving refuse-particles pre-. clpitating from the zone in normal operation on a metallic surface disposed at a distance above an ashreceiving surface in said cham- 4o ber andoutof the normal path of the fiamingf fuel. and directly exposedto the combustion zone except for residues from'said zone deposited thereon in normal operation, and

i subjecting the particles during and subse 4 5 ciluentL to their lodgment on saidmetallic surace to the action of a cooling medium-serving to lower the temperature of said particles below that of substantial coalescence. l In testimony whereoflail'ix my signature.

-HARRY RAYMQIND COLLINS. 

